An organic electroluminescent display device (OLED) usually includes a plurality of pixels, and each pixel is composed of several light emitting areas. Currently, one widely used solution in small and medium sized devices is forming a pixel with three sub-pixels of red, green and blue. In order to obtain high pixel resolution, the three types of light emitting areas of red, green and blue need to be evaporation coated respectively by using high precision masks, and therefore three sets of precision metal masks are needed. But the highest precision of a precision metal mask is limited by processing levels, which causes that the resolution of organic electroluminescent display devices is difficult to increase. In another aspect, because the precision mask has a high precision and every light emitting area needs aligning and adjustment, while each time of adjustment causes the finished product ratio of display devices to decrease, the device cost is increased and the realization of higher resolution is limited.
A relatively better solution of device configuration in the art is using a shared blue light emitting layer, as shown in FIG. 1, the light emitting layer of an OLED device includes three types of light emitting areas of red, green and blue, wherein the red light emitting area 16 and the green light emitting area 15 is arranged in a juxtaposed manner on a hole transport layer, a part of the blue light emitting layer 7 is arranged on the hole transport layer, and other parts of the blue light emitting layer 7 covers the red light emitting area 16 and the green light emitting area 15. During preparation, two sets of precision masks are respectively used to form the red light emitting area 16 and the green light emitting area 15, and then an ordinary open mask is used for evaporation coating of the blue light emitting layer 7. This solution requires three times of evaporation coating (i.e. changing the mask for 3 times), and the masks used for prepare the red and green light emitting areas need to be precision masks. Although one less set of precision mask is used in this solution, it still needs to use two sets of precision masks for two sets of single-colored sub-pixels, and it still needs three times of aligning, which reduces the resolution of the display device.
Currently, the best mode of pixel arrangement in the art is the IGNIS mode, wherein each pixel is composed of red, green and blue (RGB) sub-pixels arranged in a triangular shape, as shown in FIG. 3. This pixel arrangement mode notably increases the resolution, but still cannot reach a resolution higher than 400 pixels per inch (PPI).